Screw conveyor



July 27, 1965 c. LEWIS ETAL 3,197,015

SCREW CONVEYOR Filed May 9, 1963 2 Sheets-Sheet 1 F'IGJ GEORGE L.- OSWELL. JAMES JONAKIN ATTORNEY y 1965 E. c. LEWIS ETAL 3,197,015

SCREW CONVEYOR Filed y 1963 2 Sheets-Sheet 2 UNVENTORS EVERETT C- LEWIS GEORGE L- OSWEILL. JAMES JONAKIN ATTORNEY United States Patent Ofiice 3,197,815 Patented July 27, 1965 SCREW CONVEYOR Everett C. Lewis, Avon, George L. Oswell, Somers, and James Jonakiu, Simsbury, Conn., assignors to Combustion Engineering, Inc., Windsor, Conn, a corporation of Delaware Filed May 9, 1963, Ser. No. 279,252 8 Claims. (Cl. 198-43) This invention relates to conveyor mechanism and particularly to mechanism for conveying the solids discharge from a centrifuge, such as the partially dewatered coal centrifuged from a liquid-solid slurry of crushed coal and water pumpable over long lengths of pipeline.

An object of this invention is conveyor mechanism which will transport a pasty type of material which has a property of building up in, or sticking to, the conveyor mechanism.

Another object is conveyor mechanism including an elongated, rotatable, open-center, self-supporting spiral ribbon cantilever conveyor loosely fitting the conveyor channel in which it rotates and conveys material.

A still further object is conveyor mechanism having a flexible wall and means for agitating the wall to prevent accumulation of material. 7

Other objects and advantages will be apparent from the following specification and the attached drawings in which:

FIG. 1 is an end view partly in section of mechanism incorporating the invention and showing the flexible wall and the spiral conveyor; and FIG. 2 is a side view of the mechanism partly in section, showing the centrifuge discharge, the flexible wall and the spiral conveyor. I In the handling of pipeline coal and the supplying of this coal to a furnace for burning therein, as for example the furnace of a vapor generator, the coal slurry as it is conveyed through the long pipeline is of a consistency which makes it desirable to remove a portion of the water prior to introducing the same into a firing system of a furnace. This concentration of the coal slurry may be effected by means of a centrifuge dewatering device, and the concentrate egressing from the centrifuge may be conveyed to a furnace, such as a cyclone furnace, for burning therein or to a grinding mill and thence to a furnace. For details with relation to such systems for the handling and burning of coal thus transported through a pipeline, reference ismade to US. application Serial No. 159,600 filed December 15, 1961, in the names of James Jonakin and Robert C. Tulis, and US. application Serial No. 159,603 filed December 15, 1961, in the name of James Jonakin.

The partially dewatered solid portion of the slurry may be thrown outwardly from the discharge orifices of the centrifuge and collected in a rotating trough surrounding the discharge orifices. A stationary scraper blade may be positioned to scrape the layer of centrifuged coal from the interior of the rotating trough and discharge this coal axially, or side-wise, from the rotating drum in a free falling stream having a horizontal component to a trough or chute from which it may be conveyed to the mill or furnace for eventual burning. Reference may be made to U.S. application Serial No. 215,203 filed August 6, 1962 in the names of Harry B. Jones and Donald J. Frey for Method and Apparatus for Handling Pipeline Coal for a more detailed description of such a mechanism. For purposes of illustration but not limitation the present invention is shown in combination with, and receiving coal from a device of the type shown in the Jones and Frey application.

The pipeline slurry is fed into a rotating centrifuge drum 18 in which water is separated from the coal and discharged into a hopper 12 and conveyed away through pipe 14 to a point of discharge or further treatment. The partially dewatered coal is discharged outwardly from the orifices 16 into a rotating gutter 18 surrounding the orifices 16. The discharge material, of pasty consistency, collects around the interior periphery of the slowly rotating gutter 18. A partition 20 secured to and forming part of the housing member 22 for the centrifuge extends from the housing member 22 to adjacent the periphery of the flange 24 of the centrifuge drum 10 and acts as a closure for the open end of the gutter 18. The stationary scraper blade 26 is secured to the partition 20 and extends through an opening 28 in the partition 20 into the gutter 18. The scraper 26 is positioned in the gutter, and shaped to scrape the accumulated coal from theinterior peripheral surfaces of the gutter 18 and from the sides of the back wall 28 of the rotating gutter. The scraper 26 discharges the dewatered slurry in a stream side-wise or axially and downwardly.

Because of the somewhat pasty or sticky nature of the partially dewatered slurry it has a tendency to stick or accumulate on the walls or surfaces of chutes or conveyors utilized in conveying or directing the coal from the centrifuge to the mill or furnace. This is particularly disadvantageous because if it does not completely block the chute or conveyor it will accumulate and periodically let go in a manner which will seriously interfere with the continuous and uniform feeding of the coal to the mill or furnace. These slugs of coal as they pass through the system will distort the fuel-air ratio and interfere with efiicient combustion.

In order to assure a uniform flow of coal applicants have provided a flexible wall 30 substantially normal to said discharged stream against which some of the coal directed by the chute 26 impinges and have provided a nonclogging screw conveyor 32 operating in a trough or chute 34 substantially parallel to said wall and agitating the flexible wall 30 to prevent any accumulation of the pasty material.

A plate 36 extends across and is secured to the casing 22 and acts as a partition or fixed wall below the rotating bowl 10, An angle iron 38 is secured to the partition 36 and extends transversely across the casing 22. A plurality of flexible strips or niembersof any suitable material, such as metal chains 40,. are secured'to and suspended from the angle iron 38, preferablyin a'double row so as to form a dependent flexible wall extending across the casing 22 in the chamber 42 receiving coal from the scraper 26. A trough or chute 34 of any suitable material such as metal, preferably arranged at an angle, is positioned under, and completely downstream of, the exit of the scraper 26 and the Wall 30 to receive dewatered coal dropped in a free falling stream from the scraper 26 or the flexible wall 38. The trough is preferably semicircular and may have a suitable casing connecting it with the chamber 42, receiving coal from the scraper 26, and forming a chamber enclosing the flexible wall 30 and the trough 34. A screw conveyor 32 is supported in a hearing 44 forrotation about the axis of said screw by any suitable means such as a motor 46. The conveyor loosely fits the trough and forms a cantilever supported at only one end, the other end being guided only by the trough. The conveyor forms a hollow cage-like structure completely open at one end, except for a spacing bar connecting the ends of the rods, extending in a spiral lengthwise of the conveyor, defining the outline of the cage and forming substantially the entire conveyor.

The preferably metal rods or ribbons 48, of which there are preferably two or more for mechanical strength, are positioned or spaced by spacing bars and are secured at one end to a spacing bar or flange 52 driven by the shaft 54 supported in the bearing 44. The ribbons 48 are selfesupporting, no center shaft is required, and form a cantilever. supported in the bearing .44. The chains 40 hanging down from the cross member 38 have their free ends extending by gravity into the path of rotation of the members 48 so that, as the members 43 rotate, they will pick up the loose ends of the chains, carry them a short distance toward the center of the casing enclosing the chute and chain and then 'drop them thus agitating the chain and displacing any of the dewatered somewhat pasty slurry that might otherwise accumulate on the wall. Because of the skeleton nature, or cage-like formation, of the open center ribbon conveyor, there is not sufiicient exposed surface on the conveyor to permit any material accumulation of dewatered coal thereon. Any material which did tend to accumulate on the conveyor would either be knocked off by the chains or would drop off under the influence of gravity as the ribbon was passing over the trough. If any binding should occur, particularly near the lower end of the conveyor, the spirally extending rods would tend to unwind and reduce diameter thus acting to clear itself. This open center screw conveyor formed of spirally extending rods without a center shaft, and hence being self-sustaining, and supported at only one end in a bearing and substantially free floating at the other end has been found to .provide an entirely satisfactory screw conveyor for a pasty type of material such as dewatered coal and provides. a screw conveyor with some flexibility in torsion which will overcome any catching or binding action.

While we have illustrated and described bodiment of our invention, it is to be understood that such is merely illustrative and not restrictive and that variations and modifications may be made therein without departing from the spirit and scope of the invention. We therefore do not wish to be limited to the precise details set forth but desire to avail ourselves of such changes as fall within the purview of our invention as defined in the fol lowing claims. a

We claim:

1. In combination a semi-circular conveyor trough terminating at an axially open discharge end, a rotatable conveyor screw rotatable about an axis having an axially open end loosely fitting said trough and terminating at said axially open end of thejtrough so as to discharge conveyed materialout of said trough open end, said screw comprising a rod extending in a spiral around the axis of rotation of said conveyor and spaced from said axis, a plurality of closely spaced flexible elements suspended from one end above said trough and screw and out of contact with conveyed material in said trough and means for agitating said elements. I

2. In combination a conveyor trough, a conveyor screw in said trough, said screw comprising a self-supporting ribbon'rotatably supported in a bearing at one end for rotation in said trough around an axis, said ribbon arranged in a spiral along and spaced from said axis to form said conveyor screw and having a radial transverse dimension materially less than the radius of said screw, a substantially vertical wall comprising a plurality of flexible elements arranged above said trough and screw :and out of contact with said trough and conveyed material in said trough and means for agitating said elements.

3. In combination with means discharging pasty maa preferred emterial in a stream, a flexible vertical wall receiving some of the discharged material, a trough under said stream and wall, an open center rotatable screw conveyor, comprising an open ended cage-like structure formed of spirally extending rods, in said trough, said flexible wall comprising flexible elements upstream of, and receiving said pasty material before, said trough and hanging down into the path of travel of said rods.

4. In combination with means discharging pasty material in a stream, a flexible vertical wall receiving some of the discharged material, a trough under said stream and wall, an open center, open ended, rotatable screw conveyor, having a screw portion comprising a spiral selfsupporting rod spaced from the axis of rotation of said conveyor, driving means connected with and supporting one end of said rod, said screw loosely fitting said trough, said flexible wall arranged in a plane substantially transverse and normal to said stream and substantially parallel to the axis of said conveyor and comprising a plurality of separate flexible elements hanging down into the path of travel of said rods.

5. In combination with a centrifuge discharging partiaily dewatered coal in a stream having a horizontal com-' ponent, a plurality of closely spaced flexible elements suspended to intercept and prevent further horizontal travel of said stream of discharged coal and direct said entire stream of coal in a downward path, and means independent of said coal for agitating said elements to dislodge adhering coal.

6. A combination as claimed in claim 5 including a screw conveyor located beneath the discharge from said.

centrifuge and beneath said flexible elements to receive said discharged coal by gravity from said centrifuge and said elements and including a rotating conveyor element contacting said flexible elements to provide said agitating means.

7. In combination, a conveyor, means, having a discharge orifice spaced from said conveyor, for discharging a stream of pasty material and providing a free falling stream of discharged material-having a horizontal component, between said orifice and said conveyor, a flexible dependent wall intercepting, and preventing further, horizontal travel of said stream and converting said stream into a substantially vertical free falling stream, said conveyor positioned downstream of said orifice and wall and means for agitating said wall to dislodge adhering material.

' 8. A combination as claimed in claim 7 in which the conveyor is a screw conveyor having a rotating screw and the agitating means comprises upper portions of said rotating screw contacting the lower edge of said flexible wall.

References Cited by the Examiner UNITED STATES PATENTS 326,769 9/85 McClurg 198-213 2,009,734 7/35 Hiller 198213 2,837,194 6/58 Ross 222-228 FOREIGN PATENTS 801,304 9/58 Great Britain.

SAMUEL F. COLEMAN, Primary Examiner.

WILLIAM B. LA BORDE, Examiner. 

1. IN COMBINATION A SEMI-CIRCULAR CONVEYOR TROUGH TERMINATING AT AN AXIALLY OPEN DISCHARGE END, A ROTATABLE CONVEYOR SCREW ROTATABLE ABOUT AN AXIS HAVING AN AXIALLY OPEN END LOSSELY FITTING SAID TROUGH AND TERMINATING AT SAID AXIALLY OPEN END OF THE TROUGH SO AS TO DISCHARGE CONVEYED MATERIAL OUT OF SAID TROUGH OPEN END, SAID SCREW COMPRISING A ROD EXTENDING IN A SPIRAL AROUND THE AXIS OF ROTATION OF SAID CONVEYOR AND SPACED FROM SAID AXIS, A PLURALITY OF CLOSELY SPACED FLEXIBLE ELEMENTS SUSPENEDE FROM ONE END ABOVE SAID TROUGH AND SCREW AND OUT OF CONTACT WITH CONVEYED MATERIAL IN SAID THROUGH AND MEANS FOR AGITATING SAID ELEMENTS 